We have tested Civilization VI (steam) on Windows 10 1803 updated version and found that there is no problem with hooking DirectX 12 games.

Please uninstall Bandicam and install the latest version of Bandicam and try recording again.If it does not seem to work, please let us know if you are able to record the game in windowed mode.Also, please let us know if you have the same issue with other DirectX 12 games.